In manufacturing a semiconductor device, a film forming processing or an etching processing is performed using a plasma processing apparatus on a semiconductor wafer (hereinafter, simply referred to as a “wafer”) as a workpiece. In the film forming processing or the etching processing, a gas is introduced into a vacuum processing chamber in which the wafer is accommodated, and a plasma processing is performed on the wafer by plasma of the gas.
In the processing container in which the plasma processing is performed, various factors may raise abnormal discharge (e.g., arc discharge), or reaction products attached to components in the processing container may be peeled off so that particles may be generated. Any of these may cause wafer defects.
Further, the plasma processing is used in a step at a relatively upstream side of the semiconductor device manufacture. Thus, when there is an abnormality in the plasma processing, the wafer processing may be continuously performed until the abnormality is found in a defect inspection step downstream of the above-mentioned step. As a result, a large number of defective wafers are produced during that period so that the yield of products is reduced. Therefore, it is required to stably perform the plasma processing and detect an abnormality in the plasma processing at an early stage.
Therefore, for example, Patent Document 1 has suggested a method for diagnosing a state of a plasma processing apparatus by monitoring a predetermined parameter while a plasma processing is performed in the plasma processing apparatus. According to the method of Patent Document 1, the plasma processing is performed on a dummy wafer for inspection by using a recipe for state diagnosis to acquire a predetermined parameter. Then, the presence/absence of abnormality of the plasma processing apparatus is diagnosed by comparing the acquired parameter with a parameter previously acquired in a state where there is no abnormality in the apparatus.